James Boole: Fell 6,000ft and lived to tell the tale. Photograph: Francesca Cao

By any reasonable standards, people who jump out of planes are reckless or suicidal; and people who jump out of planes flying at low altitude over volcanos, well, they're beyond help. But that was our plan that day.

I was working on a documentary, filming an athlete skydiving over the Kamchatka in Russia. Known as "the land of fire and ice", it has 40 or so active volcanos, and is ­ covered in snow for nine months a year. The idea was to get footage of the athlete "flying" in front of a column of steam hundreds of feet high that was spewing from a vent in the side of a mountain.

During my 12 years in the sport, I've completed around 2,500 jumps, and at that time I was doing it four or five times a week. But there's no room for complacency. Our plan was to exit at 6,000ft, fly past the steam, open our parachutes at between 150 and 200 metres, and land. But after we jumped out of the helicopter, the plan wasn't followed.

I was very focused on my filming and had a viewfinder over my left eye, to help frame the video. To gauge distances, you really need both eyes, and because of the snow covering the volcano it was very difficult to sense height – all we could see was white.

Quite suddenly, I realised I could see the texture of the snow and ice, meaning I had two or three seconds before I hit the ground. I can't have been more than 20 metres up. Terror gripped my heart and stomach, the darkest of darkness. Then I had a clear thought of my wife and three-month-old daughter, and was overwhelmed by sadness as I felt the parachute lift from my back. I'd opened it without even thinking, just as you might instinctively hit the brakes in a car, and experienced a brief sense of hope. This is going to hurt a lot, I thought, or not at all.

The parachute barely unfurled, but swung my feet up above me, like a child on a swing. Then the ground hit me full in the back with the force of a truck. The impact left me unconscious for a few seconds, and as I opened my eyes two overwhelming emotions raced through me. The first was elation at having survived, the second black, jagged fear. I was certain, straight away, that I'd broken my back – the pain in my spine was so immense that I had no doubt about this at all.

We had a crew of about a dozen, mountain guides with first aid and a stretcher, but it took some time for the helicopter to find a safe spot to land and for them to carry me to it. I left a 1m-deep crater in the snow.Meanwhile, the athlete had drifted safely down beside me – his parachute had opened at the correct time.

I'd become very cold, and one of my lungs had filled with blood, which gurgled in my airways. I thought it likely that I had serious internal bleeding and was about to die. I tried to decide what my last words to my family should be – "I'm sorry this has happened, I love you" – then wondered who in the multinational crew to pass them on to. I ended up choosing an Austrian guy who seemed to have the most fluent English.

It took an hour to reach the local hospital, where a diagnosis wasn't forthcoming, and another nine to fly on to Moscow, where a CT scan confirmed my back was broken. There was better news, though – it was a stable fracture and I appeared to have suffered no neural damage.

I flew back to the UK for the rest of my treatment. I was fitted with a back brace, and was up and walking within a week. In the six months since, I've had a lot of time to consider my jumping from other perspectives. I've lived a very internalised life – most of my friends and people I talk to are jumpers, and my whole life has revolved around this extreme sport, this dangerous environment. I've been able to reflect on how it's seen by others, and on my motivation for doing it. My wife, Christina, is also an active skydiver and base jumper, and has jumped since my accident.

In a month or so, I should be fit enough to jump again. I'll definitely do one more, then see how I feel. My conflict at the moment is to define a balance between having a family and following my passion. I really miss it. How could I not? It's the closest realisation of Icarus's dream – you put on a suit and you fly.